1. Field
The embodiment generally relates to power consumption analyzing methods and computer-readable storage media, and more particularly to a power consumption analyzing method that is suited for analysis and estimation of a power consumption during a development stage of a semiconductor integrated circuit, and to a computer-readable storage medium which stores a program for causing a computer to carry out such a power consumption analyzing method.
2. Description of the Related Art
Recently, it has become important to reduce the power consumption of semiconductor integrated circuits to cope with the increased circuit scale and to enable use in portable equipments that are driven by batteries.
Generally, the logic operation of the semiconductor integrated circuit is designed by Register Transfer Level (RTL) in the Hardware Description Language (HDL). In the RTL design stage, the architecture of the circuit needs to be determined as the specifications, and the power consumption of the circuit is affected by the structure of the architecture. Accordingly, it is necessary to study and evaluate whether or not the architecture of the circuit is an optimum architecture from the point of view of reducing the power consumption, in the RTL design stage or in a stage prior to the RTL design stage.
In the recent semiconductor integrated circuits, the gated clock, which blocks the input of the clock to the flip-flop, is employed in order to reduce the power consumption. As methods of inserting the gated clock, there is a method in which the designer explicitly inserts the gated clock in the RTL description stage, a method in which a logic synthesis tool inserts the gated clock by automatically transforming an enable signal of the flip-flop during a synthesis process, and a method which combines these two methods. As the performance of the logic synthesis tool improves, it is expected that the mainstream of the design flow will insert the gated clock using the logic synthesis tool.
For example, a Japanese Laid-Open Patent Application No. 2002-92065 proposes a circuit design method which inserts the gated clock with respect to the flip-flop.
FIG. 1 is a diagram for explaining a conventional semiconductor integrated circuit developing procedure. The developing procedure shown on the left side in FIG. 1 includes an RTL design stage 1, a logic synthesis stage 2, a net list generating stage 3, a layout generating stage 4, and a net list generating stage 5. It is assumed for the sake of convenience that the logic synthesis stage 2 inserts the gated clock with respect to the semiconductor integrated circuit by using a logic synthesis tool.
FIG. 2 is a diagram showing a power consumption analysis result 11 that is obtained by analyzing the power consumption of modules m1 through m3 in the RTL design stage 1, where the modules m1 through m3 are function units forming the circuit in the RTL design stage 1. In FIG. 2, the ordinate indicates the power consumption in mV, and the abscissa indicates the simulation cycle in arbitrary units. On the other hand, FIG. 3 is a diagram showing a power consumption analysis result 12 that is obtained by analyzing the power consumption of modules m1 through m3 in the net list generating stage 5, where the modules m1 through m3 are function units forming the circuit in the net list generating stage 5. In FIG. 3, the ordinate indicates the power consumption in mV, and the abscissa indicates the simulation cycle in arbitrary units. In addition, the measured result of the power consumption of the semiconductor integrated circuit that is created after the developing procedure, that is, the actual device, becomes approximately the same as the power consumption analysis result 12.
In the logic synthesis stage 2, when inserting the gate clock with respect to the semiconductor integrated circuit using the logic synthesis tool, considerable differences are introduced between the power consumption analysis result 11 in the RTL design stage 1 and the power consumption analysis result 12 in the net list generating stage 5 after the logic synthesis stage 2 for the power consumption value, the power consumption change, the power consumption ratio between the modules forming the circuit and the like, due to the effects of the gated clock that is inserted with respect to the circuit in the logic synthesis stage 2, as may be seen by comparing the power consumption analysis results 11 and 12 shown in FIGS. 2 and 3.
According to the semiconductor integrated circuit developing procedure, the power consumption analysis result in the RTL design stage and the power consumption analysis result in the net list generating stage after the logic synthesis stage greatly differ, due to the effects of the gate clock that is inserted with respect to the circuit in the logic synthesis stage. For this reason, even if the architecture of the circuit is modified in the RTL design stage in order to reduce the power consumption, it is difficult to comprehend the extent to which the modification of the architecture affects the actual device, and there was a problem in that it is difficult to optimize the architecture of the circuit in the RTL design stage.